Trapezoidal Magnet Pole Assembly for Cooler Axial Flux Rotors

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Solution Overview

Problem

Existing axial flux electric machines face challenges in cooling the rotor, particularly when made of magnets, due to eddy currents generated by rotation, which can lead to demagnetization from excessive heating, and current control, while current manufacturing methods are complex and costly.

Innovation Solution

A method and system for manufacturing trapezoidal magnet poles using commercially available magnets, involving grooving, bonding, and overmolding to reduce eddy currents and heating, while optimizing magnetic properties and mechanical reinforcement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If segmented magnet poles are used to reduce eddy currents and heating, then rotor heating is reduced, but the magnet poles become irregular and magnetic performance deteriorates

Engineering Contradiction:
Improve rotor heatingVSAvoidmagnetic performance
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

The magnet pole is divided into multiple segments (first magnet segment, second magnet segment, third magnet segment) that are arranged and bonded together. This segmentation reduces eddy currents within the pole structure while maintaining the overall pole shape and magnetic performance through proper arrangement and bonding of segments.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses asymmetric arrangement of magnet segments with different orientations. The first magnet segment has magnetization in a first direction, the second magnet segment has magnetization in a second direction, creating an asymmetric magnetic structure that optimizes both eddy current reduction and magnetic performance.

Inventive Principle:
Principle #4Asymmetry

2Manufacturing precision

If complex assembly processes are used to achieve optimal magnetic properties, then magnetic performance is improved, but manufacturing cost and complexity increase

Engineering Contradiction:
Improvemagnetic propertiesVSAvoidassembly process
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Multiple magnet segments are bonded together to form a complete magnet pole structure. The bonding process merges the individual segments into a unified assembly that achieves optimal magnetic properties through the combined arrangement of segments with different magnetization directions.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The magnet segments are pre-configured with specific magnetization directions and arrangements before final assembly. This preliminary preparation of segments allows for optimized magnetic performance to be achieved through a relatively simple bonding process rather than complex post-assembly adjustments.

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method achieves reduced manufacturing costs and improved magnetic performance with better axial symmetry, enhancing the cooling and mechanical stability of the rotor.

Implementation Method 1

a step of grooving said magnet block capable of promoting said step of sectioning said magnet block

Methodology Applied
Scientific EffectStress concentration:

Implementation Method 2

a step of bonding the rows of unit magnets to each other... the glue sent by said glue injection means being capable of sliding under a row of unit magnets in formation and thus gluing said row of unit magnets in formation to the underlying row of unit magnets

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Implementation Method 3

a step of separation of said structure of unit magnets into two identical trapezoidal poles

Methodology Applied
Scientific EffectMechanical cutting:

Implementation Method 4

said separation step is followed by a step of overmolding said trapezoidal poles with resin, capable of giving an arcuate shape to the external radial end of said poles after overmolding

Methodology Applied
Scientific EffectOvermolding:

Data Source

PatentEP3929951B1Method and system for manufacturing magnetic poles
Publication Date: 2025.10.08 AMPERE SAS
  • EP3929951B1 patent drawingFigure 1
  • EP3929951B1 patent drawingFigure 2
  • EP3929951B1 patent drawingFigure 3

AI summary

The invention relates to a method for manufacturing magnet poles for an axial flux electric machine, said magnet poles being formed of identical oblong unit magnets, magnetically oriented longitudinally, said method comprising a step of forming rows of unit magnets by gluing said unit magnets together along one of their longitudinal surfaces of the same section, said method being characterized in that it further comprises the steps of: - gluing (E4) said rows of unit magnets to each other, while maintaining said rows of unit magnets inclined with respect to a plane comprising the longitudinal edges of the first unit magnets of each of said rows, until forming a parallelogram-shaped structure of unit magnets, - separating (E5) said structure of unit magnets into two identical trapezoidal poles.